19
Thresholding
Certain loggers can be programmed to start logging when the readings of one
sensor go above or below a certain threshold. This option may be enabled by
choosing
Start ABOVE threshold
or
Start BELOW threshold
from the
Thresholding
drop-
down selection box.
Loggers with Firmware
version 4.3 (introduced
Nov. 19, 2002) or
greater have a Profiling Power Save (PPS) feature that greatly reduces the
amount of power consumed when thresholding is enabled. Earlier Firmware
versions leave the sensors on when waiting for the thresholding condition to be
met. Versions 4.3 and greater, however, can be programmed to turn the sensors
on and off at a user specified rate. For example, the logger can be told to wake
up every 10 seconds to check whether it has passed the threshold, and to sleep
in the meanwhile. When the reading reaches the threshold the logger will start
sampling and recording data until either the end time is reached or the threshold
conditions are no longer met, whichever comes first.
Loggers with Firmware version 4.20 or higher have an additional thresholding
option called
Hysteresis
. This feature causes the logger to keep sampling for a
user-specified time period even if the thresholding conditions are no longer being
met. For instance, the logger may be programmed to start logging when it
makes contact with the water and to continue to log for a time even if the
changing height of the water surface (wave action) causes it to briefly come out
of the water.
Note:
Thresholding is not available on auto-ranging sensors (page 21).
Note
: When
thresholding
is enabled,
the logger
cannot be
programmed
to perform
averaging.
